Stop sensitive retractor

ABSTRACT

A seat belt reel urged into wound position is prevented from unwinding by a lock bar engaging ratchet teeth formed on the reel. A reset cam on a speed reducing gear mechanism driven by the reel holds the lock bar away from the ratchet teeth when the belt is fully wound to permit initial unwinding of the belt. A pair of disks rotating with the reel are viscously connected to a disk pivotally mounted on the reel shaft, so that the pivotal disk is urged to rotate with the reel. A finger on the pivotal disk holds the lock bar out of engagement with the ratchet teeth during initial unwinding of the belt. Upon interruption of the unwinding movement, a spring urges the pivotal disk to pivot to release the lock bar and to cause the lock bar to engage the ratchet teeth so that further unwinding of the reel is prevented. The reset gear mechanism includes an inner gear eccentrically mounted on the reel shaft and restrained from rotation so that it moves in an orbital path. An outer gear is provided with a ring of teeth surrounding the teeth of the inner gear and which are dimensioned to mesh with the teeth of the inner gear so that as the inner gear moves in its orbital path, the outer gear rotates one tooth for each cycle of the inner gear. The outer gear has more teeth than the inner, with the result that the outer gear rotates. The reset cam which is formed on the outer gear is angularly oriented and the speed reducing gears are so arranged to only hold the lock bar out of engagement with the ratchet teeth when the belt is near its fully wound position.

United States Patent 1 1 Yang 1 1 STOP SENSITIVE RETRACTOR [75]Inventor: Elmer Chen-Sheng Yang, Anaheim,

Calif.

[73] Assignee: Pacific Scientific Company Anaheim, Calif.

22 Filed: Feb. 17, 1971 21 Appl.No.: 116,092

[52] US. Cl. 242/107.4 [51] Int. Cl A62b 35/00 [58] Field 01 Search242/107 SB, 107.4,

[56] References Cited UNITED STATES PATENTS 3,558,075 1/1971 Stoffel242/l07.4 3,598,336 8/1971 Frost 242/107.4 3,289,970 12/1966 Board etal. 242/l07.4 3,412,952 11/1968 Wohlert et al 242/107.4

Primary ExaminerWerner H. Schroeder Attorney-Fowler, Knobbe & Martens [57] ABSTRACT A seat belt reel urged into wound position is prevented fromunwinding by a lock bar engaging ratchet teeth July 17,1973

formed on the reel. A reset cam on a speed reducing gear mechanismdriven by the reel holds the lock bar away from the ratchet teeth whenthe belt is fully wound to permit initial unwinding of the belt. A pairof disks rotating with the reel are viscously connected to a diskpivotally mounted on the reel shaft, so that the pivotal disk is urgedto rotate with the reel. A finger on the pivotal disk holds the lock barout of engagement with the ratchet teeth during initial unwinding of thebelt. Upon interruption of the unwinding movement, a spring urges thepivotal disk to pivot to release the lock bar and to cause the lock barto engage the ratchet teeth so that further unwinding of the reel isprevented.

The reset gear mechanism includes an inner gear eccentrically mounted onthe reel shaft and restrained from rotation so that it moves in anorbital path. An outer gear is provided with a ring of teeth surroundingthe teeth of the inner gear and which are dimensioned to mesh with theteeth of the inner gear so that as the inner gear moves in its orbitalpath, the outer gear rotates one tooth for each cycle of the inner gear.The outer gear has more teeth than the inner, with the result that theouter gear rotates. The reset cam which is formed on the outer gear isangularly oriented and the speed reducing gears are so arranged to onlyhold the lock bar out'of engagement with the ratchet teeth when the beltis near its fully wound position.

31 Claims, 12 Drawing Figures STOP SENSITIVE RETRACTOR This inventionrelates to a retractor for a seat belt or other restraining element, andmore specifically, to an improved arrangement for preventing furtherunwinding of a seat belt once it has been initially unwound to a desiredposition. The invention further relates to an improved arrangement forpermitting initial unwinding of the belt and for resetting the meanswhich initiates the locking of the belt after the unwinding.

Early versions of the seat belt retractors performed only the basicfunction of retracting the belt when it was released, the seat beltbeing locked in its operative position by manual means. However, manyadditional requirements have since been established for retractors, aprimary one being that of performing automatic belt locking functions toprevent further unwinding of the belt after it has been initiallyadjusted. Various types of retractors have been developed for thispurpose including those which remain unlocked until rapid decelerationoccurs and then operate on an inertia principle; and those whichautomatically lock with slight retracting movement or with apredetermined time delay after start of initial unwinding.

While there are many advantages of these various arrangements, they allhave shortcomings. Accordingly, a need exists for a retractor which willautomatically lock the belt without having the characteristics of thetypes mentioned. That is, without requiring inertia forces, someretracting movement of the belt, or a predetermined delay to elapse fromthe time that unwinding commences. An overriding consideration for anyretractor is that it should be highly reliable while yet being simple tooperate and inexpensive to manufacture. Another requirement whichbecomes important, particularly in the use of retractors for aircraft isthat the mechanism should be compact and lightweight.

In accordance with the structure and method of the present inventionthere is provided a retractor which is sensitive to the stoppingmovement of a belt or other restraining element at the end of initialunwinding or adjustment of the belt. That is, as soon as the unwindingmovement is interrupted, the retractor locking mechanism is initiated sothat further unwinding is immediately prevented. More specifically, in apreferred arrangement the retractor includes a belt wound on a flexiblestorage member such as a reel rotatably mounted on a support. A springor other power means normally urges the belt into its fully woundposition. A look such as a bar pivotally mounted on the support ismovable into engagement with ratchet teeth on the reel. Means areprovided to sense the interruption of initial unwinding movement andinitiate movement of the bar into locking position.

. A reset cam driven by the reel through a speed reducing mechanismassociated with movement of the reel is employed to permit initialunwinding of the reel. A pair of disks are mounted in face to facerelation on the reel shaft with a layer of viscous material betweenthem. One of the disks is fixed to rotate with the reel shaft while theother disk is pivotally mounted on the shaft. The viscous medium causesthe pivotal disk to rotate with the other; however, stops are providedto permit only limited pivotal movement of the driven disk. The pivotalor driven disk is provided with means for cooperating with the lock bar.Upon initial unwinding movement of the reel the pivotal disk is moved aslight distance with the rotating disk into a position where it holdsthe lock bar out of engagement with the ratchet teeth on the reel. Whenthe unwinding movement is interrupted, a spring urges the pivotal diskagainst the viscous drag of the viscous medium into a position whereinthe locking bar can engage the ratchet teeth to prevent furtherunwinding movement.

Upon release, the belt is automatically retracted and the reset cam,whose movement is responsive to the rotation of the reel, engages thelock bar to render it inoperative when the reel approaches its fullywound position. This cam is mounted on a gear which is rotatably mountedon the reel shaft and which includes an inwardly extending ring of teeththat mate with teeth on an inner gear that is eccentrically mounted onthe reel. The inner gear is restrained from rotation so that it moves inan orbital path and the diameter of the ring of teeth in the outer gearis dimensioned to mesh with the teeth of the inner gear as it is movedin its orbital path. By providing the outer gear with more teeth thanthe inner gear, a very effective speed reducing mechanism is provided,so that one revolution of the reel produces only limited rotationalmovement of the outer gear. Hence by properly positioning the cam onthis outer gear, and obtaining the desired speed reduction, the cam isonly moved to hold the locking bar out of engagement with the ratchetteeth when the belt is in its fully wound position. Thus, the resetmechanism provides a unique means for rendering a function inoperativeduring a certain zone of rotational operation.

For a more thorough understanding of the invention, refer now to thefollowing detailed description and drawings in which:

FIG. 1 is a perspective view of the exterior of the seat belt retractorof the invention illustrating the lock bar and the configuration of theoverall assembly;

FIG. 2 is a cross-sectional view of the retractor of FIG. 1 taken online 22 showing the retractor mechanism in cross-section;

FIG. 3 is an exploded perspective view showing the stop sensitivemechanism and the reset mechanism;

FIG. 4 is a perspective view of the interior of the outer gear of thereset mechanism;

FIG. 5 is a cross-sectional view of the spring end of the retractortaken on line S5 of FIG. 2;

FIG. 6 is a cross-sectional view of the reset mechanism on line 6-6 ofFIG. 2;

FIG. 7-10 are cross-sectional views on line 6-6 showing the gears of thereset mechanism in various operational positions with respect to eachother and the lock bar;

FIG. 11 is an end elevational view on line 11-11 of FIG. 2 illustratingthe pivotal disk of the stop sensitive mechanism in its one extremeposition in solid lines and in its other position in phantom lines andwith the lock bar in its unlocked position; and

FIG. 12 is a view similar to that of FIG. 11 but with the lock bar shownin its locked position.

Referring first to FIGS. 1 and 2, the novel apparatus which embodiesthis invention includes a U-shaped support 10 preferably made ofaluminum or other strong lightweight material. A storage member in thefonn of a spool like reel 12 is rotatably mounted in the support 10 withthe reel shaft 13 extending through the support. A spiral power spring14 encircles one end of the shaft 13 of the reel 12, one end of thespring being secured to the shaft while the other end of the spring issecured to a cap 16 attached to the support. A flexible restrainingelement in the form of a webbing or belt 18 has one end secured to thereel 12 to wind the belt 18 onto the reel. A spring 20 shown in FIG. 2on the shaft 13 rotates with the reel and axially positions the reelwith respect to the support 10.

The spool ends of the reel are formed with ratchet teeth 2] to beengaged by a lock bar 22 having its ends pivotally mounted in thesupport 10. Referring to FIG. 5, the slot 23 in one leg of the supportcan be seen to be dimensioned so as to permit the lock bar to pivot'into and put of engagement with the ratchet teeth while beingrestrained from translational movement in the plane of the support legs.Referring to FIG. 3, the other slot 24 in the leg 10b is similar to theslot 23, but it also forms the end of an elongated slot 25 serving adifferent function.

The novel mechanisms of the invention are essentially enclosed within ahousing 26 mounted on the left leg 10b of the support 10 as viewed inFIG. 1. Basically these include the stop sensitive mechanism of theinvention generally indicated at 28 in FIG. 2, positioned on the outerend of the shaft 13, and a reset mechanism generally indicated at 30,positioned on the shaft 13 between the mechanism 28 and the support leg10b.

Referring now to FIG. 3 as well as to FIG. 2, the stop sensitivemechanism 28 may be seen to include a pair of disks 31 and 32 which areprovided with centrally located straight sided apertures 33 and mountedon a flat sided portion 13a of the shaft 13 to rotate with the shaft-Sandwiched between the disks 31 and32 is a middle disk 34rotatably-mounted on a washer like spacer 35 which in turn is rotatablymounted on the shaft section 13a. A thin layer of grease or otherviscous material 36 is applied to both faces of the middle disk 34 incontact with the rotating disks 3] and 32, the spacer 35 being slightlythicker than the disk to provide space for the viscous material. Ifdesired, the spacer 35 can be formed integral with the disk 34, and withthe same thickness as the disk, the viscous material would then provideits own spacing.

A pair of circumferentially spaced fingers 38 and 40 formed on themiddle disk 34 extend radially beyond the periphery of the disks 31 and32. A notch 40a is formed in the radially outer corner of the finger 40on the edge facing the finger 38.

Still referring to FIG. 3, the reset mechanism 30 includes a pair ofspeed changing gears, an inner gear 42 and an outer gear 44. The innergear 42 includes a central aperture 45 for mounting the gear on acircular section 13b which is eccentrically formed on the shaft 13. Theouter gear44 is mounted on a circular section 130 which isconcentrically formed on the shaft.

The inner gear 42 includes a ring of radially extending teeth 46 mountedon a plate 48, the plate including a portion 48a which extends radiallyoutwardly from the remainder of the plate. An axially extending pin 48bmounted on the plate extends into the elongated slot 25 formed in theleg I0!) of the support I0. The pin 48!) prevents rotation of the innergear 42, but it permits the orbital movement of the gear produced by theeccentric section 1312 of the shaft as the shaft rotates.

Referring now to FIG. 4, as well as to FIG. 3, it can be seen that theouter gear 44 is formed in the shape of a shallow cup like member havinga ring of gear teeth 50 which are formed to mesh with the teeth 46 ofthe inner gear. The inner diameter of the ring of teeth 50 is sized toaccommodate the orbital movement of the teeth 46 while continuing tomesh with the teeth. In the arrangement shown, the outer gear 44 isformed with 10 teeth 50 whereas the inner gear 42 is formed with nineteeth 46. Also formed on the outer gear 44 is a cam 54 which extendsradially outwardly from the remainder of the outer gear and extendscircumferen tially about 45.

Mounted on the end of the lock bar 22 which extends through the slot 24in the support leg 10b is a crank arm 56 which forms an extension of thebar. The arm 56 includes a radially extending portion that extendsbetween the stop sensitive mechanism 28 and the reset mechanism 30having a pair of stop pins 58 and 60 mounted thereon extending parallelto the axis of the lock bar and parallel to the shaft 13. The stop pin58 extends outwardly toward the pivotal disk 34 of the stop sensitivemechanism 28. The stop pin 60 includes one end 600 which extends towardthe pivotal disk 34 and an opposite end 60b which extends to the otherside into the rotational path of the cam 54 on the outer gear 44. Thestop pins 58 and 60 are spaced a distance less than the distance betweenthe fingers 38 and 40 of the pivotal disk 34, as may be seen from FIG.I2. As seen from FIGS. 2, 3 and 6, the other end 60b of the stop pin 60is in the path of the cam 54.

Sandwiched between the rotating disk 32 and the outer gear 44 is aspring 64 which forms part of the stop sensitive mechanism. The springhas a central coiled section 640 which surrounds the shaft section 13ctogether with the outer gear 44. The spring 64 further includes aradially extending arm 64b having an axially extending segment 64c onits outer end which is positioned within a hole 380 in the finger 38 ofthe nonrotating disk 34. The other end of the spring 64 is in the formof an arm 64d which engages the stop pin 58 on the side of the pin 58facing the stop pin 60a. The orientation of this spring 64 is such as tourge the finger 38 on the pivotal disk 34 towards and into engagementwith the stop pin 58 into the position shown in FIG. 12. Thus, if thepivotal disk 34 is moved away from the stop pin 58, the spring 64produces torque on the crank arm 56 to pivot the lock bar 22 into itslocking position engaging the ratchet teeth 21 on the reel 12.Correspondingly, if the lock bar 22 is held in its unlocked position,the spring 64 produces torque on the pivotal disk 34 to cause it to movein a counter-clockwise direction as viewed in FIGS. 3 and 12.

The various components of the stop sensitive mechanism 28 and the resetmechanism 30 are axially confined on the shaft 13 between the supportleg 10b and a suitable retaining element 68 which snaps over the end ofthe shaft section 13a. The spring central coiled section 64a isformedwith its convolutions normally axially spaced and they are axiallycompressed when the retaining element 68 is in place. Thus the springsection 64a eliminates axial play in both the viscous drag assembly andthe gear assembly.

OPERATION When not in use, the seat belt I8 is normally fully wound onthe reel 12 under the urging of the power spring 14. In this conditionthe lock bar 22 is in an un locked position out of engagement with theratchet teeth 21, as shown in FIG. 1 l. The major portion of the lockbar 22 is shown in dotted lines in FIG. II as are the ratchet teeth. Thecam 54 on the outer gear 44 of the reset mechanism 30 is only partiallyseen in FIG.

11, and for the sake of clarity is not shown in dashed lines. However,the cam 54 is shown in FIG. 6 engaging the pin 60 on the crank arm 56attached to the lock bar 22 so that the lock bar 22 cannot pivot in acounterclockwise direction as viewed in FIGS. 6 and 11, with the resultthat the lock bar is positively held in an unlocked condition. It shouldbe noted that the lock bar 22 is normally in the unlocked position atthis stage, in any event, due to the fact that the finger 38 on thepivotal disk 34 of the stop sensitive mechanism is urged into engagementwith the stop pin 58 of the crank arm 56 by the spring 64 as shown insolid lines in FIG. 11; and, the non-rotating disk 34 has been urgedinto a counter-clockwise direction as the reel 12 was moving in acounter-clockwise direction while the belt was being retracted from itsprevious use.

Upon commencement of unwinding rotation of the reel 12, the stopsensitive mechanism 28 urges the lock bar 22 into its locked position.That is, by applying an unwinding force to the belt 18, the reel 12 ismoved in a clockwise direction as viewed in FIG. 11. The disks 31 and 32of the stop sensitive mechanism rotate with the reel and the viscousmedium 36 between the rotating disks 31 and 32 produces torque throughfriction on the disk 34 causing it to want to follow the rotation of therotating disks 31 and 32.

This torque moves the driven or pivotal disk 34 clockwise into thephantom line position shown in FIG. 11. The spring 64 through its arm64d urges the pin 58 to follow the finger 38 on the disk 34, thusproducing a force urging the lock bar 22 to pivot counterclockwise intolocking position. However, the cam 54 on the outer gear 44 of the resetmechanism 30 prevents movement of the bar 22. Further, the rotation ofthe disk 34 moves its finger 40 so that its notch 40a receives the stoppin 60 and thus prevents counterclockwise movement of the lock bar 22into the locking position. Thus, the reel with its disks 31 and 32 isfree to continue to move in an unwinding direction. Further rotation ofthe disk 34, however, is prevented by the stop pin 60 within the notch400. Since the distance between axis of rotation of the disk 34 and thepivotal axis of the bar 22 is less than the distance between axis of thedisk 34 and the notch 40a plus the distance between the axis of the bar22 and the stop 60, the bar 22 and the disk 34 are in effect holdingeach other from further movement in this dynamic unwinding condition.Note that at the beginning of the unwinding movement, the lock bar 22 isheld in the unlocked position, both by the cam 54 and the disk 34.

This unwinding rotation will cause the cam 54 to move in a clockwisedirection also by virtue of the gears of the reset mechanism 30. Morespecifically, referring to FIG. 6, the clockwise rotation of the shaft13 causes its eccentric section 13b to move in an orbital path carryingthe inner gear 42 of the reset mechanism. Since the inner gear 42 isrestrained from rotation by virtue of its pin 48b being held in the slot25 of the support leg b, the gear teeth 46 simply remain in the positionindicated in FIG. 6 except that the entire gear moves in an orbitalpath, as indicated by the broken line 70 in FIG. 6. This causes theteeth 46 on the inner gear 42 to walk around the interior of the outergear 44 engaging its teeth 50. Since the outer gear 44 has one moretooth 50 than does the inner gear 42, one revolution of the eccentric13b causes the outer gear 44 to move through a distance of one tooth andone space in a clockwise direction. This movement in turn causes the cam54 to be moved that amount. Thus, sufficient unwinding movement willcause the cam 54 to move out of engagement with the stop pin connectedto the lock bar with the result that the lock bar will no longer bepositively held in the unlocked position by the cam.

To further explain the operation of the gears of the reset mechanism,they are shown in various operational conditions in FIGS. 6 through 10.In FIG. 6 tooth 46a of the inner gear is shown in full mesh betweenteeth 50a and 50j of the outer gear. Tooth 46a is in this positionbecause the portion of the eccentric 13b which is furthest from the axis71 of rotation of the shaft 13 is at that time radially aligned with thetooth 46a. However, the tooth 46d is not in complete meshing relationwith the teeth 50c and 50d of the outer gear.

However, turning to FIG. 7 it can be seen that the eccentric l3b hasrotated counter-clockwise a little less than half a revolution to apoint where tooth 46d is now fully meshed between the teeth 50c and 50dof the outer gear. Thus it can be appreciated that the outer gear hasbeen rotated in a clockwise direction a distance slightly less than onetooth during rotation of the eccentric 13b through a little less thanrevolution. The corresponding movement of the clockwise movement of thecam 54 can be seen by comparing the relative position of the stop 60 onthe cam 54 between FIG. 6 and FIG. 7. In FIG. 7 the stop 60 is nearingthe trailing edge of the cam 54. The lock bar 22 is still held inunlocked position by the cam in FIG. 7.

Referring to FIG. 8, the eccentric 13b continues to rotate in aclockwise direction causing the inner gear tooth 46g to move into fullmesh between the teeth 50g and 50f of the outer gear. By comparingposition of the teeth of FIG. 6 with that of FIG. 8, it can be seen thatthe tooth 46g of the inner gear was ahead of the tooth 50g in FIG. 6,but that the outer gear has rotated into the position of FIG. 8 wherethe tooth 50g of the outer gear is ahead of the tooth 46g of the innergear. Correspondingly the stop 60 on the crank arm 56 is shown at thetrailing edge of the cam 54 still positively holding the lock bar 22 inan unlocked position.

In FIG. ,9, the eccentric 13b has now completed one revolution so thatit is back to the position shown in FIG. 6. The outer gear, however, hasbeen rotated an angular distance of that between corresponding points ontwo adjacent teeth of theteeth 50 of the outer gear. Thus, the tooth 46aof the inner gear is shown in FIG. 9 in complete mesh between the teethSIM and 50j of the outer gear while the tooth 50a has moved from aposition immediately in front of the tooth 460, as in FIG. 6, to aposition immediately in front of the tooth 46b as shown in FIG. 9.

Since there are ten teeth 50 in the outer gear and nine teeth 46 in theinner gear, it can be seen that one revolution of the eccentric 13b hasrotated the outer gear a fraction of a revolution about the concentricshaft section 130. The denominator of the fraction being the number ofteeth in the outer gear or 10 and the numerator being the differencebetween the outer and the inner, or 1. Hence, in the present case thisis a ten to one speed reduction which has been obtained by utilizingonly two gears. Advantageously, the rounded gear teeth need not have aprecision fit for this kind of meshing and can be molded of plastic.Such manufacturing conveniences are of great importance in high volumeproduction. Moreover, if desired, greater speed reduction can beobtained by increasing the number of teeth in the two gears while stillhaving the outer gear with one more tooth than the inner. The desiredspeed reduction is balanced with the circumferential length of the cam54 to provide the desired amount of unwinding rotation of the belt inwhich the lock bar 22 is positively held in the unlocked position by thecam. For a typical lap belt operation, it is desirable that the belt canbe unwound about 8 to 10 inches before locking can possibly take placein that a belt must usually be unwound at least that amount to belatched with its mating buckle. Thus is can be seen that this so calleddead zone of the locking mechanism can be easily set for whatever amountof belt unwinding is desired.

Continued unwinding rotation slowly moves the cam 54 away from the pin60, as may be seen in FIG. 10. It should be noted that the cam does notrotate far enough to engage the stop pin 60 a second time duringunwinding of the belt in that this would interfere with the lockingfunction of the retractor. Thus it is important that the reset mechanism30 be capable of providing adequate speed reduction since the reelrevolves many times in unwinding a belt, for most applications.

Returning now to the operation of the stop sensitive mechanism 38, ashas been described in connection with FIGS. 9 and 10, the lock bar 22 isno longer held by the cam 54, but so long as the belt is beingcontinually unwound with sufficient velocity to hold the disk 34 throughthe viscous medium, in the position indicated by the phantom lines inFIG. 11, the lock bar 22 continues to be held in the unlocked positionby the notch 40a in the finger 40. That is, the viscous drag, caused bythe unwinding velocity, must continue to be greater than the force ofthe spring 64 acting on the disk in the other direction.

Once the desired amount of belt has been unwound so that the disks 31and 32 of the stop sensitive mechanism stop moving, the spring arm 64dsenses the substantial reduction in velocity upon interruption ofmovement, with the result that the spring quickly snaps the finger 38and the pin 58 into engagement, releases the pin 60 from the notch 40ain the finger 40 and snaps the lock bar 22 into locked position. Ifunwinding tension is once more applied to the belt, the lock bar 22 dueto the urging of the spring 64, is held in the locked position with theratchet teeth.

In unwinding or drawing out of a seat belt, the user often pulls outmore belt than is needed; and after the belt is buckled and released,the power spring 14 of FIG. 2 will automatically retract the belt into asnug condition on the user. More specifically, this retracting movementcauses the reel to move in a counterclockwise direction as viewed in FIG1 1, which in turn causes the disks 31 and 32 to move with the reel, andthe viscous connection between the disks 31 and 32 and the disk 34produces a counter-clockwise torque on the disk 34. This causes the disk34 to pivot with its finger 38 moving the pin 58, and thus pivoting thelock bar clockwise into its unlocked position. Thus, the belt is free toretract and advantageously the retracting occurs free of ratchet noise.The movement of the lock 22 is limited by the support 10, and thus thepin 58 being engaged by the finger 38 limits winding movement of thedisk 34.

If now the vehicle is subjected to rapid deceleration causing the userof the seat belt to be thrown forwardly applying sudden tension on thebelt, a torque is immediately produced on the reel 12 and on the disks31 and 32 attached to the reel shaft which produces a torque through theviscous medium 36 on the disk 34, and causes the disk 34 to start tomove in a clockwise or unwinding direction. The spring arm 64d urges thestop pin 58 to follow the finger 38 with the result that a torque isproduced on crank arm 56 snapping the lock bar 22 into locking positionso that it engages the next ratchet tooth. This condition is shown inFIG. 12. Note also, referring to FIG. 10, the movement of the lock barwithin its slot in the support leg 10b and the fact that the cam 54 isnot in position to restrict movement of the lock bar into the lockingposition. If the tension remains on the seat belt, the lock bar willremain in the position shown in FIG. 12. However, if the tension isrelaxed so that there is any slight retraction of the belt as producedby the power spring 14, the disk 34 will move in a counter-clockwisedirection a slight amount due to the torque produced by the rotatingdisks 3] and 32 which will move the lock bar into the unlocked solidline position of FIG. 12 once again. This occurs because the torqueresistance of the lock bar is less than the torque produced by theviscous medium. If tension is once more applied to the belt, the lockbar will immediately snap into locked position to prevent further unwinding of the belt.

When the seat belt is unbuckled and released, the power spring 14automatically rotates the reel in a winding direction until the belt isfully wound. During this winding movement the reset mechanism 30functions in a reverse direction from that described above so that thecam 54 returns to the position shown in FIG. 6 once more holding orblocking the lock bar in its unlocked position so that the seat belt isonce more in condition to be unwound.

What is claimed is:

l. A retracting device comprising a support, a storage member rotatablymounted on the support, a flexible restraining element wound on thestorage member, power means urging the storage member in the direc tionto wind the restraining element on the storage member, lock meansmounted on the support and movable into position to prevent the storagemember from rotating to unwind the restraining element after initialunwinding, and means for initiating operation of said lock means solelyupon the stopping of the unwinding rotation of the storage member andthereby prevent further unwinding of the restraining element.-

2. A retracting device comprising a support, a storage member rotatablymounted on the support, a flexible restraining element wound on thestorage member, power means urging the storage member in the directionto wind the restraining element 'on the storage member, lock meansmounted on the support and movable into position to prevent the storagemember from rotating to unwind the restraining element after initialunwinding, and means sensitive to the stopping of the unwinding rotationof the storage member to initiate operation of said lock means andthereby prevent further unwinding of the restraining element, said stopsensitive means includes means for urging said lock means into operationas unwinding force is applied to the restraining element, and meansresponsive to unwinding movement of the restraining element to block theoperation of the lock means during initial unwinding movement from afully wound position, said stop sensitive means sensing the stopping ofthe unwinding motion to release the lock means and thereby allow thelock means to prevent further unwinding.

3. A retracting device comprising a support, a storage member rotatablymounted on the support, a flexible restraining element wound on thestorage member, power means urging the storage member in the directionto wind the restraining element on the storage member, lock meansmounted on the support and movable into position to prevent the storagemember from rotating to unwind the restraining element after initialunwinding, and means sensitive to the stopping of the unwinding rotationof the storage member to initiate operation of said lock means andthereby prevent further unwinding of the restraining element, said stopsensitive means includes movable means mounted on said storage member ina manner to move from a first position to a second position duringinitial unwinding rotation of the storage member, and spring means forurging the movable means to the first position upon stopping of theinitial unwinding rotation of the storage member, the urging by saidspring being used to initiate operation of the locking means.

4. The device of claim 3 wherein said movable means renders the lockmeans ineffective when in said second position.

5. The device of claim 3 wherein said movable means comprises a diskrotatably mounted on the storage member to pivot between said first andsecond positions, the disk being movable by frictional engagement withmeans fixed to rotate with the storage member.

6. The device of claim 3 wherein said spring means urges said lock meansinto locking position as it urges the movable means towards its firstposition.

7. The device of claim 1 including reset means for rendering the lockmeans ineffective as the restraining element approaches its fully woundcondition.

8. A safety belt retractor including a support, a reel mounted on thesupport, a belt mounted on the reel, a retraction spring mounted on thesupport urging the reel in a direction to retract the belt, a lockmounted on the support for preventing unwinding of the belt, theimprovement comprising:

means for rendering the lock ineffective when the belt is retracted soas to permit initial unwinding of the belt, said means being renderedineffective after a predetermined initial amount of unwinding rotationof the belt; and

stop sensitive means for keeping the lock ineffective as the belt isbeing unwound and including means responsive solely to the interruptionof the unwinding rotation of the reel for releasing the lock to preventfurther unwinding of the belt after the interruption.

9. A safety belt retractor including a support, a reel mounted on thesupport, a belt mounted on the reel, a

retraction spring mounted on the support urging the terruption of theunwinding rotation of the reel for releasing the lock to prevent furtherunwinding of the belt after the interruption, said stop sensitive meansincludes:

a first disk mounted to rotate with the reel;

a second disk pivotally mounted on the same axis as the rotating disk,the disks being positioned in face to face relation with a layer ofviscous material in between such that rotation of the rotating diskcauses the pivotally mounted disk to rotate to the extent of its limitedmovement, the movement of said pivotally mounted disk which occursduring the unwinding movement of the reel being utilized to hold thelock out of engagement with the reel when the belt is initiallywithdrawn from a fully retracted position; and

spring means urging said pivotally mounted disk in a belt windingdirection against the drag of the viscous material to release the lockbar when the unwinding movement of the belt is interrupted, the springmeans urging the pivotally mounted disk to move against the drag of theviscous material to release the lock.

10. The retractor of claim 8 wherein said means for rendering the lockineffective when the belt is retracted includes cam means movable inresponse to rotation of the reel.

11. A safety belt retractor including a support, a reel mounted on thesupport, a belt mounted on the reel, a retraction spring mounted on thesupport urging the reel in a direction to retract the belt, a lockmounted on the support to be urged into engagement with the reel toprevent protraction of the belt, the improvement comprising:

a first disk mounted to rotate with the reel;

a second disk mounted on the same axis as the first disk but beingmounted to rotate independently of the reel, the disks being positionedin face to face relation with a layer of viscous material in betweensuch that rotation of the first disk causes the second disk to rotatebecause of the viscous material;

an extension fixed to move with the lock;

a finger formed on said second disk engaging the extension for holdingthe lock out of engagement with the reel once the belt is started to beunwound from a retracted position;

spring means urging said second disk into position with respect to saidextension to move the lock into engagement with the reel when theunwinding movement of the belt is interrupted; and

cam means for engaging said extension to hold the lock out of engagementwith the reel when the reel has been rotated to a position wherein thebelt is substantially fully retracted to permit initial unwinding.

12. The retractor of claim 11 including reset means responsive torotation of the reel for moving said cam means.

13. The retractor of claim 12 wherein said reset means comprises a pairof speed reducing gears positioned adjacent one end of said support andadjacent said disks, and with said extension being positioned betweenthe gears and the disks, said spring means being coiled around the shaftbetween the disk and the gears and having one end linked to the seconddisk and the other end engaging the lock extension.

14. A safety belt retractor including a support, a reel having a shaftmounted on the support having ratchet teeth mounted to rotate with thereel, a belt mounted on the reel, a retraction spring mounted on thesupport urging the reel in a direction to retract the belt, a lock barmounted on the support being movable into engagement with the ratchetteeth to prevent unwinding of the belt, the improvement comprising:

a pair of disks mounted on one end of the reel shaft to rotate with theshaft;

a disk rotatably mounted on the shaft between and in face to facecontact with said pair of disks and with viscous material between thecontacting surfaces of the disks such that rotation of the pair of disksurges the middle disk to rotate with them because of the viscousmaterial, said stop sensitive disk having a pair of circumferentiallyspaced fingers extending radially beyond the periphery of the pair ofdisks;

a crank arm mounted on an end of said lock bar to form an extension ofthe bar, said crank arm having a pair of spaced pins which extendparallel to the reel shaft and are positioned between the fingersof saidmiddle disk in the rotational path of the fingers to thereby form twostops for limiting the movement of the middle disk to pivotal action,one of the pins limiting the movement of the middle disk in a beltunwinding direction and the other pin lirniting the movement in windingdirection; and

a spring urging the pin which limits the movement of the middle disk inthe belt winding direction into engagement with the adjacent finger ofthe middle disk said spring urging the middle disk in the belt windingdirection and urging the lock bar into locking position when unwindingtension is applied to the belt.

15. The retractor of claim 14 wherein the finger on said middle diskwhich engages the pin that limits unwinding movement of the middle diskincludes a notch formed to receive said pin which limits unwindingmovement when the middle disk is urged to move in an unwindingdirection, the notch serving to prevent movement of the lock bar intolocking engagement with the ratchet teeth.

16. The retractor of claim 14, a reset mechanism mounted on said shaftfor holding said lock bar out of engagement with the ratchet teeth whenthe belt approaches its fully wound condition, said reset mechanismincluding gear means movable in response to rotation of the shaft andcam means movable by said gear means in a path to engage said lock barextension and hold the lock bar out of engagement with the ratchet teethwhen the belt approaches its fully wound position.

17. The retractor of claim 16 wherein said cam means is mounted on oneof the gears and said gear means includes two gears which reduce therotational speed of the shaft such that the cam means only restrictsmovement of the lock bar when the belt is substantially fully wound onthe reel.

18. The retractor of claim 16 wherein said shaft has an eccentricallymounted section; and said gear means includes an inner gear mounted onsaid eccentric section, the inner gear being attached to said support ina manner to restrain the gear from rotation while permitting it to movein the orbital path produced by the rotation of said eccentric section,said inner gear including a plurality of radially extending teeth, andan outer gear rotatably and concentrically mounted on the shaft, aplurality of teeth forming a ring surrounding the teeth on said innergear and arranged and shaped so that the inner gear teeth mesh with theouter gear teeth as the inner gear moves in its orbital path, the outergear having more teeth than the inner gear so that it is rotated as theshaft rotates but at a reduced rate of speed, and said cam means isrotated by said outer gear.

19. In a retractor having locking means for preventing unwinding of aflexible element such as a belt on a reel, an improved means forrendering the locking means ineffective in a predetermined zone of theunwinding movement of the belt comprising:

an inner gear having a ring of outwardly extending teeth;

an outer gear having teeth dimensioned to mesh with the teeth of theinner gear and arranged in a ring surrounding the inner gear teeth withthe outer gear having more teeth than the inner gear, the gears beingrotatably mounted on the shaft of the belt reel, said shaft having meansfor eccentrically mounting the gears with respect to each other, meansrestraining one of the gears from rotation while the other is permittedto rotate, the diameter of the ring formed in the outer gear being suchthat the orbital movement produced by the eccentric mounting causes theteeth of the inner gear to mesh with the teeth of the outer gear duringthe orbital movement, said orbital movement causing rotational movementof the gear which is free to rotate at a rotational speed which is lessthan that of the shaft; and

cam means moved by said rotating gear and located so that the movementof the cam is used to render the lock means ineffective in said zone.

20. The retractor of claim 19 wherein the speed reduction obtained bythe gear mechanism and the circumferential length of the cam means onthe outer gear are selected such that the cam means functions to renderthe lock means ineffective during a single zone of operation of theretractor but does not interfere with the locking function during theremaining operation of the retractor.

21. The retractor of claim 19 wherein said inner gear is eccentricallymounted on the shaft while the outer gear is concentrically mounted onthe shaft, said inner gear is restrained from rotation but is permittedto move in its orbital path produced by the eccentric mounting wherebythe orbital movement of the inner gear produces rotation of the outergear, one cycle of the inner gear being moved through its orbital pathproducing a fraction of one revolution of the outer gear, the numeratorof said fraction being the difference between the number of teeth in theinner gear and the outer gear and the denominator of the fraction beingthe number of teeth in the outer gear.

22. The retractor of claim 21 wherein:

the teeth of said inner gear are mounted on a plate which extends in aplane adjacent the plane of the gear teeth and the plate includes aportion which extends radially outwardly from the gear teeth with saidportion having a restraining pin extending parallel to the axis of thegear and received in an elongated slot which restrains rotation of thegear but permits orbital movement of the gear; and

said outer gear is in the form of a cup shaped member which fits overthe teeth of the inner gear and mates with the plate of the inner gearto thereby form an enclosed housing for the gear teeth.

23. In a seat belt retractor having locking means for preventingunwinding of a flexible element such as a belt on a reel, an improvedmeans for rendering the locking means ineffective in a predeterminedzone of unwinding movement of the belt comprising: 1

a first gear cycically driven by the rotation of said reel and a secondgear rotated by said first gear; cam means driven by the second gear torender the locking means ineffective in said zone; and

said gears being constructed and arranged to reduce the speed ofrotation of the second gear to a fraction of that of one cycle of thefirst gear, the numerator of said fraction being the difference betweenthe number of teeth in the first gear and the second gear and thedenominator of the fraction being the number of teeth in the secondgear.

24. The retractor of claim 23 including means responsive to interruptionof the initial unwinding movement for initiating operation of saidlocking means, and said cam means functions to render the locking meansineffective when said belt is in the fully retracted position.

25. A safety belt retractor including a support, a reel having a shaftrotatably mounted on the support, a belt mounted on the reel, aretraction spring mounted on the support urging the reel in a directionto wind the belt on the reel, lock means mounted on the support beingmovable into engagement with the reel to prevent unwinding of the belt,a disk rotatably mounted with respect to the reel, friction meansinterconnecting the disk and the reel to cause rotation of the disk inresponse to rotation of the reel, a pair of stops cooperating with thedisk for limiting rotation of the disk to pivotal movement between thestops, spring means for urging the disk against the stop which limitsmovement in the belt winding direction, and means interconnecting thedisk to the lock means in a manner such that the rotation of the disk inthe winding direction caused by said spring means initiates operation ofthe lock means after the belt has been initially unwound a desiredamount and the unwinding movement interrupted.

26. The retractor of claim 25 wherein said lock means comprises a lockbar pivotally mounted on said support movable into and out of engagementwith the reel and said interconnecting means includes a lock barextension arm mounted on one end of the bar, said stops being formed onsaid lock bar extension arm, and said spring means urges the lock barinto locking position with the reel.

27. The retractor of claim 26 including a disk fixed to rotate with thereel positioned adjacent said pivotal disk with a layer of viscousmaterial between the two disks for driving the pivotal disk.

28. In a seat belt having a belt wound on a reel under the urging of aspring or other power means and lock means for preventing unwinding ofthe belt, a method of automatically preventing additional unwinding ofthe belt after the belt has been initially unwound a desired amountcomprising the steps of sensing the stopping of the initial unwindingrotation of the reel; and

initiating operation of the lock means solely in response to the sensingof the stopping of the unwind ing rotation. 29. In a seat belt having abelt wound on a reel under the urging of a spring or other power meansand lock means for preventing unwinding of the belt, a method ofautomatically preventing additional unwinding of the belt after the belthas been initially unwound a desired amount comprising the steps of:

sensing the stopping of the initial unwinding rotation of the reel;

initiating operation of the lock means in response to the sensing of thestopping of the unwinding rotation;

driving a disk in the belt unwinding direction through rotation of thereel against the urging of a second spring, the disk being mounted so itcan rotate independently of the reel in response to the urging of thesecond spring; and

initiating operation of the lock means through the movement of said diskcaused by the second spring upon interruption of the initial unwindingrotation of the reel.

30. The retractor of claim 23 including means for driving said firstgear in an orbital path and means for restraining the first gear fromrotating.

31. The retractor of claim 30 wherein said first gear has a ring ofoutwardly extending teeth and said second gear surrounds the first gearand has a ring of inwardly extending teeth that mesh with the teeth ofthe first gear as it is moved in its orbital path.

I k t Disclaimer 3,746,274.-Elmer Ohm-Shem Yang, Anaheim, Calif. STOPSENSITIVE RE- TRACTOR. Patent dated July 17, 1973. Disclaimer filed Mar.8, 1974, by the assignee, Pacific Scientific Company.

Hereby enters this disclaimer to claims 1, 2, 7 8, 25, 27, 28 and 29 ofsaid patent.

[Ofiicz'al Gazette Octobcw 15,1974]

1. A retracting device comprising a support, a storage member rotatablymounted on the support, a flexible restraining element wound on thestorage member, power means urging the storage member in the directionto wind the restraining element on the storage member, lock meansmounted on the support and movable into position to prevent the storagemember from rotating to unwind the restraining element after initialunwinding, and means for initiating operation of said lock means solelyupon the stopping of the unwinding rotation of the storage member andthereby prevent further unwinding of the restraining element.
 2. Aretracting device comprising a support, a storage member rotatablymounted on the support, a flexible restraining element wound on thestorage member, power means urging the storage member in the directionto wind the restraining element on the storage member, lock meansmounted on the support and movable into position to prevent the storagemember from rotating to unwind the restraining element after initialunwinding, and means sensitive to the stopping of the unwinding rotationof the storage member to initiate operation of said lock means andthereby prevent further unwinding of the restraining element, said stopsensitive means includes means for urging said lock means into operationas unwinding force is applied to the restraining element, and meansresponsive to unwinding movement of the restraining element to block theoperation of the lock means during initial unwinding movement from afully wound position, said stop sensitive means sensing the stopping ofthe unwinding motion to release the lock means and thereby allow thelock means to prevent further unwinding.
 3. A retracting devicecomprising a support, a storage member rotatably mounted on the support,a flexible restraining element wound on the storage member, power meansurging the storage member in the direction to wind the restrainingelement on the storage member, lock means mounted on the support andmovable into position to prevent the storage member from rotating tounwind the restraining element after initial unwinding, and meanssensitive to the stopping of the unwinding rotation of the storagemember to initiate operation of said lock means and thereby preventfurther unwinding of the restraining element, said stop sensitive meansincludes movable means mounted on said storage member in a manner tomove from a first position to a second position during initial unwindingrotation of the storage member, and spring means for urging the movablemeans to the first position upon stopping of the initial unwindingrotation of the storage member, the urging by said spring being used toinitiate operation of the locking means.
 4. The device of claim 3wherein said movable means renders the Lock means ineffective when insaid second position.
 5. The device of claim 3 wherein said movablemeans comprises a disk rotatably mounted on the storage member to pivotbetween said first and second positions, the disk being movable byfrictional engagement with means fixed to rotate with the storagemember.
 6. The device of claim 3 wherein said spring means urges saidlock means into locking position as it urges the movable means towardsits first position.
 7. The device of claim 1 including reset means forrendering the lock means ineffective as the restraining elementapproaches its fully wound condition.
 8. A safety belt retractorincluding a support, a reel mounted on the support, a belt mounted onthe reel, a retraction spring mounted on the support urging the reel ina direction to retract the belt, a lock mounted on the support forpreventing unwinding of the belt, the improvement comprising: means forrendering the lock ineffective when the belt is retracted so as topermit initial unwinding of the belt, said means being renderedineffective after a predetermined initial amount of unwinding rotationof the belt; and stop sensitive means for keeping the lock ineffectiveas the belt is being unwound and including means responsive solely tothe interruption of the unwinding rotation of the reel for releasing thelock to prevent further unwinding of the belt after the interruption. 9.A safety belt retractor including a support, a reel mounted on thesupport, a belt mounted on the reel, a retraction spring mounted on thesupport urging the reel in a direction to retract the belt, a lockmounted on the support for preventing unwinding of the belt, theimprovement comprising: means for rendering the lock ineffective whenthe belt is retracted so as to permit initial unwinding of the belt,said means being rendered ineffective after a predetermined initialamount of unwinding rotation of the belt; stop sensitive means forkeeping the lock ineffective as the belt is being unwound and forsensing the interruption of the unwinding rotation of the reel forreleasing the lock to prevent further unwinding of the belt after theinterruption, said stop sensitive means includes: a first disk mountedto rotate with the reel; a second disk pivotally mounted on the sameaxis as the rotating disk, the disks being positioned in face to facerelation with a layer of viscous material in between such that rotationof the rotating disk causes the pivotally mounted disk to rotate to theextent of its limited movement, the movement of said pivotally mounteddisk which occurs during the unwinding movement of the reel beingutilized to hold the lock out of engagement with the reel when the beltis initially withdrawn from a fully retracted position; and spring meansurging said pivotally mounted disk in a belt winding direction againstthe drag of the viscous material to release the lock bar when theunwinding movement of the belt is interrupted, the spring means urgingthe pivotally mounted disk to move against the drag of the viscousmaterial to release the lock.
 10. The retractor of claim 8 wherein saidmeans for rendering the lock ineffective when the belt is retractedincludes cam means movable in response to rotation of the reel.
 11. Asafety belt retractor including a support, a reel mounted on thesupport, a belt mounted on the reel, a retraction spring mounted on thesupport urging the reel in a direction to retract the belt, a lockmounted on the support to be urged into engagement with the reel toprevent protraction of the belt, the improvement comprising: a firstdisk mounted to rotate with the reel; a second disk mounted on the sameaxis as the first disk but being mounted to rotate independently of thereel, the disks being positioned in face to face relation with a layerof viscous material in between such that rotation of the first diskcauses the second disk to rotate because of the viscous Material; anextension fixed to move with the lock; a finger formed on said seconddisk engaging the extension for holding the lock out of engagement withthe reel once the belt is started to be unwound from a retractedposition; spring means urging said second disk into position withrespect to said extension to move the lock into engagement with the reelwhen the unwinding movement of the belt is interrupted; and cam meansfor engaging said extension to hold the lock out of engagement with thereel when the reel has been rotated to a position wherein the belt issubstantially fully retracted to permit initial unwinding.
 12. Theretractor of claim 11 including reset means responsive to rotation ofthe reel for moving said cam means.
 13. The retractor of claim 12wherein said reset means comprises a pair of speed reducing gearspositioned adjacent one end of said support and adjacent said disks, andwith said extension being positioned between the gears and the disks,said spring means being coiled around the shaft between the disk and thegears and having one end linked to the second disk and the other endengaging the lock extension.
 14. A safety belt retractor including asupport, a reel having a shaft mounted on the support having ratchetteeth mounted to rotate with the reel, a belt mounted on the reel, aretraction spring mounted on the support urging the reel in a directionto retract the belt, a lock bar mounted on the support being movableinto engagement with the ratchet teeth to prevent unwinding of the belt,the improvement comprising: a pair of disks mounted on one end of thereel shaft to rotate with the shaft; a disk rotatably mounted on theshaft between and in face to face contact with said pair of disks andwith viscous material between the contacting surfaces of the disks suchthat rotation of the pair of disks urges the middle disk to rotate withthem because of the viscous material, said stop sensitive disk having apair of circumferentially spaced fingers extending radially beyond theperiphery of the pair of disks; a crank arm mounted on an end of saidlock bar to form an extension of the bar, said crank arm having a pairof spaced pins which extend parallel to the reel shaft and arepositioned between the fingers of said middle disk in the rotationalpath of the fingers to thereby form two stops for limiting the movementof the middle disk to pivotal action, one of the pins limiting themovement of the middle disk in a belt unwinding direction and the otherpin limiting the movement in winding direction; and a spring urging thepin which limits the movement of the middle disk in the belt windingdirection into engagement with the adjacent finger of the middle disksaid spring urging the middle disk in the belt winding direction andurging the lock bar into locking position when unwinding tension isapplied to the belt.
 15. The retractor of claim 14 wherein the finger onsaid middle disk which engages the pin that limits unwinding movement ofthe middle disk includes a notch formed to receive said pin which limitsunwinding movement when the middle disk is urged to move in an unwindingdirection, the notch serving to prevent movement of the lock bar intolocking engagement with the ratchet teeth.
 16. The retractor of claim14, a reset mechanism mounted on said shaft for holding said lock barout of engagement with the ratchet teeth when the belt approaches itsfully wound condition, said reset mechanism including gear means movablein response to rotation of the shaft and cam means movable by said gearmeans in a path to engage said lock bar extension and hold the lock barout of engagement with the ratchet teeth when the belt approaches itsfully wound position.
 17. The retractor of claim 16 wherein said cammeans is mounted on one of the gears and said gear means includes twogears which reduce the rotational speed of the shaft such that the cammeans only restricts movement of tHe lock bar when the belt issubstantially fully wound on the reel.
 18. The retractor of claim 16wherein said shaft has an eccentrically mounted section; and said gearmeans includes an inner gear mounted on said eccentric section, theinner gear being attached to said support in a manner to restrain thegear from rotation while permitting it to move in the orbital pathproduced by the rotation of said eccentric section, said inner gearincluding a plurality of radially extending teeth, and an outer gearrotatably and concentrically mounted on the shaft, a plurality of teethforming a ring surrounding the teeth on said inner gear and arranged andshaped so that the inner gear teeth mesh with the outer gear teeth asthe inner gear moves in its orbital path, the outer gear having moreteeth than the inner gear so that it is rotated as the shaft rotates butat a reduced rate of speed, and said cam means is rotated by said outergear.
 19. In a retractor having locking means for preventing unwindingof a flexible element such as a belt on a reel, an improved means forrendering the locking means ineffective in a predetermined zone of theunwinding movement of the belt comprising: an inner gear having a ringof outwardly extending teeth; an outer gear having teeth dimensioned tomesh with the teeth of the inner gear and arranged in a ring surroundingthe inner gear teeth with the outer gear having more teeth than theinner gear, the gears being rotatably mounted on the shaft of the beltreel, said shaft having means for eccentrically mounting the gears withrespect to each other, means restraining one of the gears from rotationwhile the other is permitted to rotate, the diameter of the ring formedin the outer gear being such that the orbital movement produced by theeccentric mounting causes the teeth of the inner gear to mesh with theteeth of the outer gear during the orbital movement, said orbitalmovement causing rotational movement of the gear which is free to rotateat a rotational speed which is less than that of the shaft; and cammeans moved by said rotating gear and located so that the movement ofthe cam is used to render the lock means ineffective in said zone. 20.The retractor of claim 19 wherein the speed reduction obtained by thegear mechanism and the circumferential length of the cam means on theouter gear are selected such that the cam means functions to render thelock means ineffective during a single zone of operation of theretractor but does not interfere with the locking function during theremaining operation of the retractor.
 21. The retractor of claim 19wherein said inner gear is eccentrically mounted on the shaft while theouter gear is concentrically mounted on the shaft, said inner gear isrestrained from rotation but is permitted to move in its orbital pathproduced by the eccentric mounting whereby the orbital movement of theinner gear produces rotation of the outer gear, one cycle of the innergear being moved through its orbital path producing a fraction of onerevolution of the outer gear, the numerator of said fraction being thedifference between the number of teeth in the inner gear and the outergear and the denominator of the fraction being the number of teeth inthe outer gear.
 22. The retractor of claim 21 wherein: the teeth of saidinner gear are mounted on a plate which extends in a plane adjacent theplane of the gear teeth and the plate includes a portion which extendsradially outwardly from the gear teeth with said portion having arestraining pin extending parallel to the axis of the gear and receivedin an elongated slot which restrains rotation of the gear but permitsorbital movement of the gear; and said outer gear is in the form of acup shaped member which fits over the teeth of the inner gear and mateswith the plate of the inner gear to thereby form an enclosed housing forthe gear teeth.
 23. In a seat belt retractor having locking means forpreventing unwinding of a flexible element such as a belt on a reel, animproved means for rendering the locking means ineffective in apredetermined zone of unwinding movement of the belt comprising: 1 afirst gear cycically driven by the rotation of said reel and a secondgear rotated by said first gear; cam means driven by the second gear torender the locking means ineffective in said zone; and said gears beingconstructed and arranged to reduce the speed of rotation of the secondgear to a fraction of that of one cycle of the first gear, the numeratorof said fraction being the difference between the number of teeth in thefirst gear and the second gear and the denominator of the fraction beingthe number of teeth in the second gear.
 24. The retractor of claim 23including means responsive to interruption of the initial unwindingmovement for initiating operation of said locking means, and said cammeans functions to render the locking means ineffective when said beltis in the fully retracted position.
 25. A safety belt retractorincluding a support, a reel having a shaft rotatably mounted on thesupport, a belt mounted on the reel, a retraction spring mounted on thesupport urging the reel in a direction to wind the belt on the reel,lock means mounted on the support being movable into engagement with thereel to prevent unwinding of the belt, a disk rotatably mounted withrespect to the reel, friction means interconnecting the disk and thereel to cause rotation of the disk in response to rotation of the reel,a pair of stops cooperating with the disk for limiting rotation of thedisk to pivotal movement between the stops, spring means for urging thedisk against the stop which limits movement in the belt windingdirection, and means interconnecting the disk to the lock means in amanner such that the rotation of the disk in the winding directioncaused by said spring means initiates operation of the lock means afterthe belt has been initially unwound a desired amount and the unwindingmovement interrupted.
 26. The retractor of claim 25 wherein said lockmeans comprises a lock bar pivotally mounted on said support movableinto and out of engagement with the reel and said interconnecting meansincludes a lock bar extension arm mounted on one end of the bar, saidstops being formed on said lock bar extension arm, and said spring meansurges the lock bar into locking position with the reel.
 27. Theretractor of claim 26 including a disk fixed to rotate with the reelpositioned adjacent said pivotal disk with a layer of viscous materialbetween the two disks for driving the pivotal disk.
 28. In a seat belthaving a belt wound on a reel under the urging of a spring or otherpower means and lock means for preventing unwinding of the belt, amethod of automatically preventing additional unwinding of the beltafter the belt has been initially unwound a desired amount comprisingthe steps of sensing the stopping of the initial unwinding rotation ofthe reel; and initiating operation of the lock means solely in responseto the sensing of the stopping of the unwinding rotation.
 29. In a seatbelt having a belt wound on a reel under the urging of a spring or otherpower means and lock means for preventing unwinding of the belt, amethod of automatically preventing additional unwinding of the beltafter the belt has been initially unwound a desired amount comprisingthe steps of: sensing the stopping of the initial unwinding rotation ofthe reel; initiating operation of the lock means in response to thesensing of the stopping of the unwinding rotation; driving a disk in thebelt unwinding direction through rotation of the reel against the urgingof a second spring, the disk being mounted so it can rotateindependently of the reel in response to the urging of the secondspring; and initiating operation of the lock means through the movementof said disk caused by the second spring upon interruption of theinitial unwinding rotation of the reel.
 30. The retractor of claim 23including means for driving said first gear in an orbital path and meansfor restraining the first gear from rotating.
 31. The retractor of claim30 wherein said first gear has a ring of outwardly extending teeth andsaid second gear surrounds the first gear and has a ring of inwardlyextending teeth that mesh with the teeth of the first gear as it ismoved in its orbital path.